The detective heading the hunt for a serial killer thought to be targeting prostitutes in Ipswich today said officers were "eager" to speak to the driver of a blue BMW.

One of the dead women, Anneli Alderton, is reported to have climbed into a blue BMW in Ipswich last week. The information was passed to police after another Ipswich prostitute reported the sighting to journalists.

Det Chief Supt Stewart Gull was today asked whether officers were "eager to speak" to the driver of that car. He replied: "We are still trying to piece together Anneli's last movements. We have received a significant volume of calls from across Suffolk and further afield and a lot of interesting information has come in. That is just one aspect we are looking at."

Mr Gull said detectives were not specifically linking the deaths of the five women to any previous killings or disappearances of prostitutes in East Anglia or in other parts of the UK.

"We are clearly aware of a number of other crimes," he said.

"We will look at any similarities but at the moment our focus is here in Suffolk and on the crimes we are currently dealing with.

"We are not at this stage linking these murders to anything else."

Mr Gull also said detectives were not "at this stage" attaching any significance to items of women's clothing handed in to police in recent days. "We need to find the clothes the murdered women were wearing and we have appealed for help with that," he said. "We have received a number of items of clothing, but we have not yet established exactly what the girls were last wearing."

But Lin Pearman, the mother of prostitute Natalie, murdered in Norwich in 1992, claimed today that police are probing a link between her daughter's death and that of the five Ipswich women.

She said: "The police have contacted me."

According to another report, the serial killer may have sent a text message on the mobile phone of a woman believed to be one of his victims, Paula Clennell, 24, to a friend who had texted her asking if she was OK.

Since December 2, five women have been found dead after being dumped in the area, prompting a massive manhunt by Suffolk Police.